A wireless communications system may generally comprise a set of “subscriber units,” typically subscriber units are the endpoints of a communication path, and a set of “base radios,” typically stationary and the intermediaries by which a communication path to a subscriber unit (SU) may be established or maintained. One such type of system is a time division multiple access (TDMA) communication system where the radio medium is divided into time slots to carry the communications of the system. Because the radio medium is a shared medium, there is a need for managing access to the radio medium and allowing the SUs to utilize the radio medium for voice communications.
Specifically, for a SU to make a transmission, the SU must first activate a base radio (BR) and acquire synchronization. Once synchronization is obtained, the SU requests that a call be setup and then transmits on the radio medium. Because activating a BR and synchronization are necessary, extra time is required to place a call. Thus, it is desirable to avoid these procedures to decrease the amount of time it takes to place a call. Further, there are cases where certain SUs need preferential access to the radio medium and need to be given access to the radio medium to transmit during the context of an active call.
Thus, there exists a need for providing access to a channel for voice communications.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to each other. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate identical elements.